1. Field of the Invention
The present invention relates to lifting or jacking mechanisms and, in particular, to a portable automotive floor jack which has inherent stability, relative insensitivity to the hardness and flatness of the jacking surface, sensitivity to the construction of modern cars, and provides a "fail safe" structure should a jacked vehicle move forward or backward while on the jack.
2. Description of the Related Art
A variety of automotive floor jacks and in particular portable floor jacks have been developed over the years in an effort to provide reliable jacking structures which minimize the strength required to jack the vehicle and are simple to operate so that use of the jack requires a minimum of skill. For example, screw jacks, screw/scissors, free standing telescoping hydraulic cylinders and a variety of hydraulic cylinder actuated lever jacks have been developed, some of which have become relatively popular. However, all of the jacking mechanisms must be supplemented with jack stands, if one is to work safely under the car, and none of the structures can be considered to be safe because of the likelihood of misuse and/or the inherent instability of the structure. In addition, many of the jacking mechanisms developed in the past were designed to lift on heavy structural members such as solid axle differential housings, ladder type frames and stout cross members. For example, the most versatile and popular jack-type, the hydraulic lever jack, is designed to lift on such structural members. However, few modern cars posses any of these characteristics and indeed few cars are now made with a frame.
Another common feature of the popular hydraulic lever jack is the use of a long handle in order to get leverage to operate the hydraulic pump. However, this makes it very difficult to use the jack in close quarters. Further, because the actuated lever translates about a pivot in the jack frame, the frame must have wheels on it to allow the frame to move to compensate for necessary translation. These four wheels must roll on a hard, smooth, flat surface if the jack is to operate properly and safely. Any other surface can create hazards since the wheels form the jack's base and the stability of the base depends on unimpeded movement on a uniformly hard and flat surface which is preferably smooth finished concrete.
It would be therefore be desirable to provide an automotive floor jack which has inherent stability, relative insensitivity to the hardness and flatness of the jacking surface by virtue of permitting the base and the lift pad to conform and adapt to less than ideal surfaces to jack between.
It would further be desirable to provide a jack structure which adjusts in angle and position to accommodate changes in angle of the vehicle as it is being jacked.